Charge accuracy (generally, about ±1.0%) of a battery has been determined by the performance of a charge control device (for example, a charge control IC or a system IC having charge control function) only.
However, it is difficult to completely eliminate manufacture variations (variation of temperature characteristics, variation of package stress, variation of implementation stress, etc.) of the charge control device. Therefore, there is a limit to enhance the charge accuracy of the battery by the charge control device only.